BISMUTH SULPHITE AGAR (as per USP)

Description

Bismuth Sulphite Agar Medium is prepared in accordance with USP and is employed for the isolation and preliminary identification of Salmonella Typhi and other Salmonellae from pathological materials, sewage, water, food and other products. Bismuth Sulphite Agar is recommended by various Associations for the isolation and preliminary identification of Salmonella Typhi and other Salmonellae from pathological materials, sewage, water, food, pharmaceutical and other products. It is a modification of Wilson and Blair medium. Salmonella Enteritidis and Salmonella Typhimurium typically grow as black colonies (rabbit eye colonies) with a surrounding metallic sheen. Salmonella Paratyphi A grow as light green colonies. This medium also favors use of larger inoculum and heavily contaminated samples as compared to other selective media, as it has unique inhibitory action towards gram-positive and coliform organisms. The medium may be inhibitory to some strains of Salmonella species and therefore should not be used as the sole selective medium for these organisms. Shigella species are mostly inhibited on this medium and also some Salmonellae like S. Sendai, S. Berta, S. Gallinarum, S. Abortus-equally are inhibited. Proteus species are inhibited but few strains give dull green or brown colonies with metallic sheen.